Present-day cosmic abundances - Dr. Karl Remeis
... An ideal alternative to find a reference for the chemical composition of cosmic matter are normal unevolved early B-type stars of ∼8-18 M⊙ , which can provide simultaneously temporal (present-day) and local (birth place) information on chemical abundances. They can be observed not only in the solar ...
... An ideal alternative to find a reference for the chemical composition of cosmic matter are normal unevolved early B-type stars of ∼8-18 M⊙ , which can provide simultaneously temporal (present-day) and local (birth place) information on chemical abundances. They can be observed not only in the solar ...
Selected observation targets at a glance per constellation
... Pi-1 Orionis, a white main sequence dwarf, type A. Pi-2 Orionis, main sequence dwarf, class A. Pi-3 Orionis: aka Tabit, is the brightest of the six, white dwarf class F. Pi-4 Orionis: a spectroscopic binary star (very close), composed of two hot class 2 stars, a giant and a subgiant. Pi-5 Orionis: b ...
... Pi-1 Orionis, a white main sequence dwarf, type A. Pi-2 Orionis, main sequence dwarf, class A. Pi-3 Orionis: aka Tabit, is the brightest of the six, white dwarf class F. Pi-4 Orionis: a spectroscopic binary star (very close), composed of two hot class 2 stars, a giant and a subgiant. Pi-5 Orionis: b ...
Brightest Stars : Discovering the Universe Through the Sky`s Most
... star’s environment of season and constellations, of earth and the sky. Each profile also offers the lore and legends connected with the star, for these are a measure of what the human race as a whole has found interesting and individual about the star. A key part of each profile, of course, is also ...
... star’s environment of season and constellations, of earth and the sky. Each profile also offers the lore and legends connected with the star, for these are a measure of what the human race as a whole has found interesting and individual about the star. A key part of each profile, of course, is also ...
Gaia 1 and 2. A pair of new satellites of the Galaxy
... Gaia-detected sources is indeed very prominent (top left and top middle panels). Note a white patch corresponding to a dearth of Gaia sources near the centre of the over-density. This is the location of Sirius, where Gaia struggles to detect genuine stars3 . The area affected by Sirius is much large ...
... Gaia-detected sources is indeed very prominent (top left and top middle panels). Note a white patch corresponding to a dearth of Gaia sources near the centre of the over-density. This is the location of Sirius, where Gaia struggles to detect genuine stars3 . The area affected by Sirius is much large ...
probing quasar environments with tunable filter
... MRC B1256-243 lack the sensitivity to probe deep into the quasar environment, but detect a number of extremely luminous objects. In BR B0019-1522, we show convincing evidence of a protocluster, including both galaxy and star formation rate densities an order of magnitude higher than that observed in ...
... MRC B1256-243 lack the sensitivity to probe deep into the quasar environment, but detect a number of extremely luminous objects. In BR B0019-1522, we show convincing evidence of a protocluster, including both galaxy and star formation rate densities an order of magnitude higher than that observed in ...
Local Universe Supernovae and Their Host Galaxies
... • occur in all type of galaxies (E included) • in spirals, not strongly associated with HII regions ...
... • occur in all type of galaxies (E included) • in spirals, not strongly associated with HII regions ...
Nikon Action Extremes 8x40, 10x50 and 12x50
... begins. Stars don't turn into slightly unfocused enlarged blobs, they elongate into curved streaks as if you were seeing a half-hour long time exposure photo pointed at the north star. At 60% out, the image is fair, OK for wide-field background, but not clear enough to see the 22" double split, it's ...
... begins. Stars don't turn into slightly unfocused enlarged blobs, they elongate into curved streaks as if you were seeing a half-hour long time exposure photo pointed at the north star. At 60% out, the image is fair, OK for wide-field background, but not clear enough to see the 22" double split, it's ...
Spitzer Spectroscopy of Circumstellar Disks in the 5 Myr Old Upper
... short wavelengths indicating that the inner ∼10 AU are cleared of primordial dust. Such excesses are more analogous to second generation, optically-thin debris disks produced by the collision of planetesimals. Of particular interest, none of the ∼30 F or G-type stars (1.2– 1.8 M⊙ ) included in the S ...
... short wavelengths indicating that the inner ∼10 AU are cleared of primordial dust. Such excesses are more analogous to second generation, optically-thin debris disks produced by the collision of planetesimals. Of particular interest, none of the ∼30 F or G-type stars (1.2– 1.8 M⊙ ) included in the S ...
Stellarium User Guide
... years now and can now be called operational. The use of a script was recognised as a perfect way of arranging a display of a sequence of astronomical events from the earliest versions of Stellarium and a simple system called the Stratoscript was implemented. The scipting facility is Stellarium’s ver ...
... years now and can now be called operational. The use of a script was recognised as a perfect way of arranging a display of a sequence of astronomical events from the earliest versions of Stellarium and a simple system called the Stratoscript was implemented. The scipting facility is Stellarium’s ver ...
The evolution of low-metallicity massive stars - Argelander
... massive stars, using theoretical simulations of the stellar structure and evolution. Evolutionary models of rotating, massive stars (9-600 M ) with an initial metal composition appropriate for the low-metallicity dwarf galaxy I Zwicky 18 are presented and analyzed. We find that the fast rotating mo ...
... massive stars, using theoretical simulations of the stellar structure and evolution. Evolutionary models of rotating, massive stars (9-600 M ) with an initial metal composition appropriate for the low-metallicity dwarf galaxy I Zwicky 18 are presented and analyzed. We find that the fast rotating mo ...
Type Ia Supernovae
... after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most e ...
... after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most e ...
The distributions and ages of refractory objects in the solar nebula
... temperatures in excess of 1350 K were maintained in the solar nebula would provide important constraints for models of its structure and evolution. For example, reaching the temperatures necessary to form refractory objects in the solar nebula requires an additional source energy beyond irradiation ...
... temperatures in excess of 1350 K were maintained in the solar nebula would provide important constraints for models of its structure and evolution. For example, reaching the temperatures necessary to form refractory objects in the solar nebula requires an additional source energy beyond irradiation ...
Hubble 2006: Science Year in Review
... The servicing mission in 1999 enhanced many of Hubble’s subsystems, including the central computer, a new solid-state data-recording system to replace the aging magnetic tape drives, and the gyroscopes needed for pointing control. A month prior to launch, a gyroscope failure had forced Hubble into ...
... The servicing mission in 1999 enhanced many of Hubble’s subsystems, including the central computer, a new solid-state data-recording system to replace the aging magnetic tape drives, and the gyroscopes needed for pointing control. A month prior to launch, a gyroscope failure had forced Hubble into ...
Radio pulsars
... than doubled the number of known pulsars • New population of high-B pulsars and new SNR associations • Globular clusters contain many millisecond pulsars • Precision timing of binary millisecond pulsars measures many properties of binary stars and tests general relativity. • Discovery of highly rela ...
... than doubled the number of known pulsars • New population of high-B pulsars and new SNR associations • Globular clusters contain many millisecond pulsars • Precision timing of binary millisecond pulsars measures many properties of binary stars and tests general relativity. • Discovery of highly rela ...
Full Text - Departement Natuurkunde en Sterrenkunde
... Strömgren photometric system . . . . . . . . . . . . . . . . . . . . . 165 ...
... Strömgren photometric system . . . . . . . . . . . . . . . . . . . . . 165 ...
Radiative Heating and Cooling in Circumstellar Envelopes
... This thesis investigates the thermal state of diluted gases being exposed to stellar radiation elds. On the basis of a steady{state non{LTE description, the radiative heating and cooling rates of the gas are determined, considering the typical densities present in circumstellar envelopes. The follo ...
... This thesis investigates the thermal state of diluted gases being exposed to stellar radiation elds. On the basis of a steady{state non{LTE description, the radiative heating and cooling rates of the gas are determined, considering the typical densities present in circumstellar envelopes. The follo ...
Tuomas Kangas
... Different ways to gain information on the progenitor stars of core-collapse supernovae are explored, with an emphasis on using the environments of supernovae. In the articles included in the thesis, various such methods are demonstrated and utilized to constrain the progenitor stars of different typ ...
... Different ways to gain information on the progenitor stars of core-collapse supernovae are explored, with an emphasis on using the environments of supernovae. In the articles included in the thesis, various such methods are demonstrated and utilized to constrain the progenitor stars of different typ ...
Molecular clumps in the W51 giant molecular cloud
... 2–1) and 13 CO (J = 2–1)]. Although some higher angular resolution observations (again of the ground state of 13 CO) have been made, these have been over smaller regions, typically surrounding one of the known H II regions within the W51 GMC (Koo 1999; Okumura et al. 2001; Sollins, Zhang & Ho 2004). ...
... 2–1) and 13 CO (J = 2–1)]. Although some higher angular resolution observations (again of the ground state of 13 CO) have been made, these have been over smaller regions, typically surrounding one of the known H II regions within the W51 GMC (Koo 1999; Okumura et al. 2001; Sollins, Zhang & Ho 2004). ...
1 Globular Cluster Systems - McMaster Physics and Astronomy
... and thus to elongate their whole distribution along the line of sight (roughly, the X axis). (3) The fundamental distance scale used by Shapley { essentially, the luminosity of the RR Lyraes or the tip of the red-giant branch { was about one magnitude brighter than the value adopted today; again, th ...
... and thus to elongate their whole distribution along the line of sight (roughly, the X axis). (3) The fundamental distance scale used by Shapley { essentially, the luminosity of the RR Lyraes or the tip of the red-giant branch { was about one magnitude brighter than the value adopted today; again, th ...
Lya escape from z~ 0.03 star-forming galaxies: the dominant role of
... their escape from galaxies. These processes can only be observed in detail out to a few ×100 Mpc. Past nearby (z < 0.3) spectroscopic studies are based on small samples and/or kinematically unresolved data. Taking advantage of the high sensitivity of HST ’s COS, we observed the Lyα lines of 20 Hα-se ...
... their escape from galaxies. These processes can only be observed in detail out to a few ×100 Mpc. Past nearby (z < 0.3) spectroscopic studies are based on small samples and/or kinematically unresolved data. Taking advantage of the high sensitivity of HST ’s COS, we observed the Lyα lines of 20 Hα-se ...
A Universal Stellar Initial Mass Function? A Critical Look Further
... The second implicit assumption is required due to finite stellar lifetimes. If one counts stars in a population spanning a large range of ages (as in the disk of the Milky Way), one can only construct the present-day mass function (PDMF). In this example, some fraction of the more massive stars with ...
... The second implicit assumption is required due to finite stellar lifetimes. If one counts stars in a population spanning a large range of ages (as in the disk of the Milky Way), one can only construct the present-day mass function (PDMF). In this example, some fraction of the more massive stars with ...
Colour-magnitude diagrams of the post
... can be considered a member. Goranskii determined a period of 0.5752 days, so that the cluster can be tentatively classified as Oosterhoff type I. 5. Conclusions Cluster parameters based on CCD photometry were derived for NGC 6256 and NGC 6717. They are both located in the bulge, but are not metal-ri ...
... can be considered a member. Goranskii determined a period of 0.5752 days, so that the cluster can be tentatively classified as Oosterhoff type I. 5. Conclusions Cluster parameters based on CCD photometry were derived for NGC 6256 and NGC 6717. They are both located in the bulge, but are not metal-ri ...
WFC3 Science White Paper - Space Telescope Science Institute
... imaging capabilities, WFC3 should provide high sensitivity and large field of view (FOV) in the near-UV and near-IR bands; (3) as a pathfinder for NGST, WFC3 will help refine the questions that NGST will answer by providing complementary UV data and the highest near-IR sensitivity available before N ...
... imaging capabilities, WFC3 should provide high sensitivity and large field of view (FOV) in the near-UV and near-IR bands; (3) as a pathfinder for NGST, WFC3 will help refine the questions that NGST will answer by providing complementary UV data and the highest near-IR sensitivity available before N ...
Clusters: age scales for stellar physics
... we cannot make experiments except in very few situations and we rely on observations and theory. Thus, observational phenomena with very well defined ages, our anchors, are extremely important. As a matter of fact, there is a scarcity of them and, moreover, several results do not agree with each oth ...
... we cannot make experiments except in very few situations and we rely on observations and theory. Thus, observational phenomena with very well defined ages, our anchors, are extremely important. As a matter of fact, there is a scarcity of them and, moreover, several results do not agree with each oth ...
H II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived blue stars forged in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. The first known H II region was the Orion Nebula, which was discovered in 1610 by Nicolas-Claude Fabri de Peiresc.H II regions are named for the large amount of ionised atomic hydrogen they contain, referred to as H II, pronounced H-two by astronomers (an H I region being neutral atomic hydrogen, and H2 being molecular hydrogen). Such regions have extremely diverse shapes, because the distribution of the stars and gas inside them is irregular. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of birthed stars such as the Pleiades.H II regions can be seen to considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of other galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In the spiral galaxies, including the Milky Way, H II regions are concentrated in the spiral arms, while in the irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.